For operating a medical imaging device, e.g. a computed tomography scanner, in many cases power has to be transmitted from a fixed device section to a movable device section. Often one or more radiation sources such as an X-ray emitter, for example, and a plurality of detectors are disposed on the movable device section, e.g. the rotating ring of a computed tomography scanner. The detectors may also be connected to imaging electronics likewise disposed on the movable device section. During operation, the movable device section can execute a movement allowing it to image one or more body parts of a patient from different perspectives.
During operation, the radiation source(s), the detectors and possibly various other consuming devices such as e.g. imaging electronics, control electronics, a cooling system, or a rotating anode drive, must be supplied with power, the power having to be transmitted from the fixed to the movable device section. Particularly in the case of a computed tomography scanner having a rotating ring which performs a plurality of rotations often in rapid succession, supplying them via a cable is not practicable, which means that a slip ring contact or inductive transfer is commonly used for this purpose.
In a computed tomography scanner, because of the differing power requirement, two separate power transmission links are normally used for supplying the X-ray emitter and for supplying the detectors and associated electronics.
In order to operate at optimum resolution, many detector types, particularly those based on doped semiconductors, require a setup time, with voltage applied, until an equilibrium has been established in the active material in the detector, and the most favorable operating point has been reached. The detectors are therefore usually kept energized even between the individual scanning operations, resulting in a relatively constant consumption baseload of up to a few kW.
The X-ray emitter, on the other hand, only requires energy during a scanning operation, but this can range from 20 kW to over 200 kW depending on the type of scan. Intensified cooling may also be necessary during a scanning operation. As this power requirement differs significantly from the baseload constituted by the detectors, the X-ray emitter is preferably supplied by a separate power transmission link.